Plug for well conductors



N 9, 19 5 J. T. ROARK 3,216,504

PLUG FOR WELL CONDUCTORS Fl 6. A r 1 11, 196

l e p l 1 2 Sheets-Sheet 1 Fig-5 INVENTOR Jo mes T. Roork wxmm Nov. 9, 1965 J. T. ROARK PLUG FOR WELL CONDUCTORS Filed April 11. 1961 2 Sheets-Sheet 2 Fig.4

INVENTOR United States Patent Ofi ice 3,216,504 Patented Nov. 9, 1965 3,216,504 PLUG FUR WELL CONDUCTORS James T. Roark, Dallas, Tex., assignor to Otis Engineering Corporation, Dallas, Tex., a corporation of Delaware Filed Apr. 11, 1961, Ser. No. 102,182 8 Claims. (Cl. 166181) This invention relates to well tools, and more particularly to a device for closing or plugging a flow conductor.

An object of the invention is to provide a new and improved plugging device for closing the bore or flow passage of a well packer.

Another object is to provide a plugging device for a well packer having a latch head which may be releasably locked in a well packer and having a plug which may be retrieved upwardly from the latch head or be ejected downwardly therefrom.

Another object is to provide a plugging device which can be installed in a well packer which has already been set in a well, or which can be installed in the packer before the packer is lowered into the well.

Still another object is to provide a new and improved plugging device which cannot be unlocked from the packer by fluid pressure differentials across the packers.

A further object is to provide a new and improved well plug which is simple to install and which will withstand pressure differentials acting in either longitudinal direction of the well bore.

A still further object is to provide a plugging device having a removable plug which is connectable to a well packer to plug the bore thereof or which is connectable to an identical plugging device previously installed in the packer, the plug of which has been previously expelled from the packer or which may be ejected therefrom by the plug portion of the plugging device to be attached thereto.

Additional objects and advantages of the invention will be readily apparent from the reading of the following description of a device constructed in accordance with the invention, and with reference to the accompanying drawings thereof, wherein:

FIGURE 1 is an elevational view, partly in longitudinal section, showing a plugging device embodying the invention suspended on a string of well tubing by a setting tool and disposed within a well casing above a well packer anchored in the well casing;

FIGURE 2 is an elevational view, partly in longitudinal section, showing the plugging device installed in the well packer;

FIGURE 3 is a view similar to FIGURE 2 showing a string of pipes lowered into the well to unlock and displace the plug of the plugging device from the packer;

FIGURE 4 is an elevational view, partly in section, showing a pair of the plugging devices connected in series, the first of which is connected to a well packer and the other of which is connected to the first;

FIGURE 5 is a plan View of a lug ring forming a part of the device;

FIGURE 6 is a plan view of a left hand releasing J slot, formed in the lower end of the setting tool;

FIGURE 7 is a plan view of right hand releasing J slot, formed on the lower end of the latch head of the device;

FIGURE 8 is a fragmentary sectional View of the upper portion of a modified form of the plugging device; and

FIGURE 9 is a fragmentary sectional view of a modified form of well packer in which the device may be installed.

Referring now particularly to FIGURE 1 of the drawings, the plugging device 10 embodying this invention is shown attache-d by a setting tool 11 to the lower end of the tubing string T. The device, which is lowerable on the tubing string into the well casing C comprises a latch head 13 and plug 14 and is receivable in the bore 15 of the mandrel 16a of the well packer 16 installed in the casing.

The plugging device 10 is adapted to close or seal the bore or flow passage of the packer as the latch head locks the device to the packer when the plug is in sealing engagement therewith. The packer 16, as shown in the drawings, is the Otis T B Production Packer, illustrated and described on page 4297 of the Composite Catalog of Oil Field Equipment and Services, 1960 Edition.

The latch head of the plugging device includes a cylindrical upper portion or latch receptacle 18 and a reduced cylindrical lower body portion 19. The latch receptacle has a bore 20 in its upper portion which communicates with a reduced diameter bore 21 of the cylindrical lower portion 19 and is coaxial therewith.

A guide ring 23 is threaded in the upper end of the upper portion of the latch receptacle. The guide ring has an external annular flange 25 which projects outwardly farther than any other portion of the device to prevent the latch head and plug of the device from engaging the casing wall and wearing thereagainst.

A lug ring 26 having inwardly projecting diametrically opposed lugs 27, as shown in FIGURE 5, is also threaded in the enlarged internally threaded bore 28 of the upper portion of the latch receptacle 18 and is held locked against the upwardly facing annular shoulder 29 in the bore of the upper portion of the latch head below the threaded bore 28 by the guide ring 23. The bore 30 of the guide ring, the bore 31 of the lug ring, and the bore 20 of the upper portion of the latch head are all of equal diameter and axially aligned so that the lower cylindrical portion 11a of the setting tool 11 may move therethrough. The lugs 27, which project inwardly of the lug ring bore 31, are receivable in the J slots 35 formed in the external surface of the lower portion 11a of the setting tool 11 whereby the device may be latched to the setting tool which, in turn, is joined to the tubing string T by a threaded connection 36. The J slots 35 cooperate with the lugs 27 to latch the device and setting tool against longitudinal movement relative to one another.

An inclined upwardly facing annular shoulder 38 in the upper portion of the latch head at the juncture of the bore 20 of the upper portion of the latch head and the reduced bore 21 of the lower portion'of the latch head is adapted to engage the bottom end 39 of the setting tool to limit the downward movement of the setting tool in the upper portion or latch receptacle of the latch head.

The expendable plug 14 of the plugging device includes a mandrel 40, the upper portion of which is received within the bore 21 of the lower portion 19 of the latch head. The plug mandrel is provided with an upwardly opening bore 41 and a plurality of lateral apertures 42 adjacent its upper end which communicate with the bore 41 and the exterior of the plug mandrel. A plurality of lat-ch balls 43, each disposed within a lateral aperture 42 of the plug mandrel have outer portions which extend into the internal annular groove 44 formed in the reduced bore 21 below the shoulder 38 in the upper portion 18 of the latch head. The latch balls are held in the outer position shown in FIGURE 1 by the external surface of a lock plunger 46 disposed in the blind bore 41 of the mandrel in order that the balls latch or lock the expendable plug 14 to the latch head 13 against longitudinal movement relative thereto. Shear screws 50 project outwardly of the lock plunger into lateral bores 51 of the plug mandrel 40 releasably to secure the lock plunger against longitudinal movement relative to the mandrel. Lateral port-s 52 are provided in the latch head and are aligned with the lateral ports 51 so that the shear screws 50 may be inserted therethrough into suitable threaded bores of the lock plunger 46.

The expendable plug 14 is thus held against longitudinal movement relative to the latch head 13 as long as the shear screws 50 are intact. However, should a downward force of suflicient strength be exerted on the lock plunger to shear the screws 50, the lock plunger will move slidably downward within the bore 41 of the plug mandrel moving the external annular recess 55 of the lock plunger into alignment with the latch balls 43 to permit the movement of the balls out of the latch head recess 44. The plug 14 is thus released for longitudinal movement in the latch head. To facilitate the movement of the balls out of the recess 44, the lower shoulder 44a of the recess is inclined downwardly and inwardly.

An external flange 60 at the upper end of the lock plunger has a downwardly facing shoulder 61 Which engages the upper end of the plug mandrel to limit the downward movement of the lock plunger relative to the plug mandrel.

The flow passage 62 of the lock plunger communicates with the bore of the tubular setting tool 11 and the bore 41 of the plug mandrel, thus preventing the creation of fluid pressure differentials across the lock plunger due to fluid pressure in the tubing T which would tend to move the lock plunger downwardly in the plug.

The lower portion 65 of the plug mandrel 40 is reduced in external diameter and is provided with a pair of packing or seal rings 66 and packing adapter rings 67 which are disposed externally on such reduced lower portion. A nut 68, threadedly attached to the lower end of the plug mandrel and secured thereto against rotation by set screws 69, holds the packing rings and the adapter rings against downward movement on. the plug mandrel. The annular shoulder 70 at the upper end of the reduced lower portion of the plug mandrel prevents upward movement of such rings on the plug mandrel. The lower end 40a of the plug mandrel is rounded and streamlined to facilitate its movement through the casing and into the well packer.

The well packer includes a lug ring 26:: which is held in the upper or latch receptacle portion 71 of the packer mandrel 16:: by a tension sleeve 72 threaded in the packer mandrel. The lug ring 26a is identical to the lug ring 26 shown in FIGURE and is similarly provided with lugs 27a.

In use, when it is desired to plug the bore 15 of the packer mandrel, the plugging device is lowered into the well packer 16 by means of the tubing T and the setting tool 11. The seal rings 66 of the plug 14 enter the bore of the packer mandrel and sealingly engage the packer mandrel to close or plug its bore or flow passage. As the device is further lowered into the packer, the lower end of the latch head 13 engages the lugs 27a of the well packer if the downwardly opening portions 73 of the J slots 75 of the latch head are not aligned with the lugs. The tubing T may then be rotated until the J slots are aligned with the lugs. As the lugs contact one or the other of cam surfaces 80 and 81 which form mouths at the lower ends of the vertical portions of the J slots, the tubing T and the latch head rotate due to the camming engagement therebetween to cause the J slots to move into alignment with the lugs and receive the lugs. As the lugs 27a enter the slots 75, the plugging device 10 is permitted to move further downwardly into the well packer until its downward movement is stopped by the engagement of the bevelled surface 82 at the lower end of the latch head 13 with the upwardly facing shoulder 83 in the bore of the latch receptacle of the packer mandrel, as illustrated in FIGURE 2. The shoulder 83, which limits the downward movement of the latch head of the plugging device 10, is identical to the shoulder 38 of the latch head 13 which limits the downward movement of the setting tool '11 in the latch head. During the downward movement of the plugging device in the well packer, the lugs 27a pass through the openings 73 of the J slots 75 to contact the inclined downwardly facing shoulder 84 in each of the slots which causes the latch head to be rotated in a counter-clockwise direction until the lugs engage the vertical shoulders 85 of the slots. In this condition, the device 10 is effectively latched in the packer by the interaction of the latch head J slots 75 and the packer lugs 27a. It will be apparent that upward movement of the latching deviec then causes the lugs 27a to bear against the lower inclined walls 86 of the slots which likewise tend to rotate the latch head 13 in a counter-clockwise direction toward the shoulders 85 to maintain the latched condition of the latch head in the packer receptacle.

If desired, the cam shoulders 80 and 81 of the two diametrically spaced J slots 75 may be inclined so that the cam shoulder 80 of one J slot and the cam shoulder 81 of the other I slot extend divergently upwardly from a sharp ridge so that these shoulders of the two I slots will cause rotational movement of the latch head 13 and the tubing string T to cause the vertical portions or openings 73 of the J slots to move into alignment with the lugs 27a upon engagement of such shoulders with the lugs.

After the packer lugs 27a engage the upper shoulders 87 of the J slots 75, the tubing T and setting tool '11 may continue further downward movement until the lower end of the setting tool comes to rest against the upwardly facing shoulder 38 in the bore of the latch head 13 of the plugging device.

At the limit of its downward movement, the tubing string T may then be rotated in a left-hand or counterclockwise direction which will tend to insure latching engagement of the packer lugs 27a in the slots 75 and consequently insure the latching of the plugging device 10 to the packer. At the same time, the counter-clockwise movement of the tubing string causes the slots 35 of the setting tool to move relative to the lugs 27 of the latch head 13 until the shoulders 90 defining one side of the vertical downwardly opening mouths 91 of the J slots 35 engage the lugs. The tubing string T and the setting tool 11 may then be readily withdrawn upwardly from the well, the lugs 27 passing through the downwardly opening mouths 91 of the J slots 35, leaving the device 10 locked to the well packer 16 and closing the bore 15 of the packer mandrel 16a against fluid flow therethrough.

It will thus be apparent that a producing geological zone located below the well packer when the plugging device 10 is latched in sealing engagement therein is effectively protected against treating fluids and any fluid pressure introduced into the casing above the well packer. Consequently, a producing zone above the packer can be cemented, acidized, fractured or otherwise treated 'without affecting the producing zone below the packer.

If desired, the plugging device may be retrieved from the well with the same tubing str-ing'T and setting tool 11 which were employed in installing the plugging device in the packer. In this case, the setting tool 11 is lowered on the end of the tubing string into the well casing until the setting tools lower end enters the bore 20 of the latch receptacle or upper portion 18 of the latch head 13 and its downward movement is arrested by the upwardly facing shoulder 38 of the latch head, the setting tool and tubing being rotated as required to align the vertical downwardly opening portions 91 of the I slots 35 with the lugs 27. Rotation of the tubing T in a clockwise manner, as seen from above, caused by engagement of the lugs 27 with the camming shoulders 92 of the slots 35 as the setting tool moves downwardly in the latch head 13 then causes the setting tool to be locked to the latch head. Upon further clockwise rotation of the tubing, the plugging device will be freed for withdrawal from the packer mandrel. The camming engagement between the lugs 27a and the camrning shoulder 84 causes the latch head to be rotated to move the vertical downwardly opening portions 73 of the slots 75 in the lower portion of the latch head into alignmnet with the lugs 27a. As the tubing T is now moved upwardly, the lugs 27a pass out of the J slots 75 in the latch head 13 so that the plugging device may then be removed from the well.

Should the packer 16 be equipped with a flapper-type valve (not shown) of the usual type at its lower end which might be closed by the lifting of the plug 14 from the packer mandrel and create a vacuum therein which might hinder the extraction of the plug, an extension may be provided on the lower end of the plug to hold the valve open until the packing rings 66 of the plug emerge from the bore of the packer mandrel.

The retrieving operation described above to unplug the packer and remove the device from the well requires a round trip of the tubing into and out of the well casing which operation is costly in both time and money. In addition, retrieval of the device from the well in this manner may be difiicult since foreign material such as sand or cement may settle around the upper end of the device and sometimes prevents its withdrawal from the packer. It is therefore generally more feasible to expel the plug 14 from the packer and allow it to fall to the bottom of the well bore. Although the plug may be made of readily drillable materials, expelling the plug 14 downwardly obviates the necessity of having to drill through the packer and the plug which is also a time consuming and costly operation.

When it is desired to forego retrieval of the device and instead expel the plug downwardly from the latch head, a tail pipe 100, a seal nipple 101, and a latch sub Hi2 are connected to the lower end of a tubing string T and lowered into the well casing, The seal nipple 101 has a plurality of resilient seal elements 103 which are adapted to seal between the seal nipple and the packer mandrel when the seal nipple is telescoped therein. The lower portion 102a of the latch sub is of the same external diameter as the lower portion 11a of the setting tool 11 and has I slots 106 formed therein which are of the same dimensions and configuration as the J slots 35 of the setting tool. When the lower end of the tail pipe 1110 contacts the upper end of the lock plunger 46 as shown in FIGURE 3 and the weight of the tubing is applied thereto, the shear screws 50 will be caused to shear, thus permitting the pipe 100 to force the lock plunger to its lowermost position wherein the plunger shoulder 61 abuts the upper end of the plug mandrel. In this relative position of the plunger and mandrel, as previously described, the alignment of the external annular recess 55 of the plunger with the balls 43 allows them to move inwardly into the recess 55 and out of the latch recess 44, thus unlocking the plug 14 from the latch head of the device, whereupon the plunger and expendable plug may be pushed downwardly through the packer mandrel to permit them to fall freely to the bottom of the well, leaving the latch head 13 in position in the packer mandrel.

Should the plug 14 fail to unlock from the packer, as might occur when foreign material has settled thereon, the settlings may be washed away by pumping liquid through the tubing string into the bore of the lock plunger whence it may pass through the lateral ports 96 of the plunger to wash away the settlings around the exterior of the plunger.

Since the tail pipe is of a diameter to fit within the bores of the latch head and packer mandrel, the tubing string may then be further lowered until the resilient seal elements 103 are disposed in the packer mandrel to seal,

thereagainst and the reduced lower portion 102a of the latch sub is disposed in the upper portion of the latch head. The J slots 106 may then be caused to receive the lugs 27 by a counter-clockwise rotation imparted to the tubing string. Thus, the connection of the latch sub to the latch head permits the tubing string T to be left in tension if desired, since the tubing is fastened to the latch sub, the latch sub to the latch head 13, and the latch head to the packer mandrel which itself is anchored firmly in the well casing. I

Since the upper portion 71 of the packer mandrel and the upper portion 18 of the latch head 13 have bores of substantially the same diameter and have lugs 27 and 27a of substantially identical configuration, it will be apparent that, as shown in FIGURE 4 a second plugging device 10a may be set in the latch head of the first plugging device after the plug thereof has been expelled from the latch head of said first plugging device in the manner previously described. Since the device 10a is substantially identical to the device 10, parts corresponding with those of the device 10 are designated by the same reference numbers to which the subscript a has been added.

The mandrel 40a of the expendable plug 14a of the second plugging device is of suflicient length that its packing elements 66a which correspond to the packing elements 66 of the plug 14, will be placed within the bore 15 of the packer mandrel in sealing relation thereto when the second plugging device is latched in the receptable of the latch head of the first device by the reception of the lugs 27 of the latch head 13 in the J slots 75a of the latch head 13a of the second plugging device. In like manner, it will be apparent that if repeated plugging of the packer in the casing becomes necessary, any number of plugging devices can be successively latched onto one another, with the I slots on the lower end of the latch head of one plugging device latching to the fastenings lugs of the latch head of the next previous plugging device. In this arrangement, of course, the last plugging device inserted to plug the well must always have a plug of sufficient length to extend into the bore of the packer mandrel to seal therewith. Even though a great number of such devices may have been connected in series, a tubing string could still be installed and placed in tension in the well casing by providing it with a latch-on sub 102 to fasten to the latch head of the upper plugging device.

It may in some circumstances be desirable to install the plugging device 10 in a packer before the packer is installed in the well. To provide for such an eventuality, the plugging device and packer may be modified as illustrated in FIGURE 8. A tension sleeve 110 in the latch head 13 of the plugging device 1% replaces the guide ring 23 normally disposed in the latch head of the plugging device 10. The tension sleeve is provided with an external thread 111 by which it may be attached to the tubing T directly, thus eliminating the setting tool 11. The tubing is disconnected from the plug by pulling upwardly on the tubing to part or rupture the tension sleeve 110 at its reduced medial wall portion in the usual manner after the packer has been set in the casing as before described.

The packer may also be modified as illustrated in FIG- URE 9. Instead of a tension sleeve, such as the tension sleeve 72 of FIGURE 1 disposed in the packer mandrel to retain the lug ring, a lock sleeve 112 may be provided to retain the lug ring 26a in the packer 16a. The plugging device may then be inserted in the packer and latched thereto as previously described.

It will thus be seen that a well plugging device has been disclosed herein which includes a plug which may 7 be retrieved from the well packer or expelled downwardly therefrom.

It will further be seen that the plugging device described herein may be installed in a well packer before or after the packer has been set in the well and that is adapted to withstand pressure differentials in either longitudinal direction of the well bore since it is releasably locked therein against movement in either longitudinal direction.

It will also be seen that a second plugging device can be installed in the latch headxof la first plugging device after the plug of the first device has been retrieved or expelled. t

It will further be seen that a second plugging device can be used to unlock and displace the plug portion of the first device.

The foregoing-description of the invention is explanatory only, and changes in the details of the construction illustrated may be made by those skilled in the art, without departing from the spirit of the invention,

What is claimed and desired to be secured by Letters Patent is:

1. As a subcombination for use in a plugging device for closing the bore of a flow conductor; an elongate latch head having a passageway extending longitudinally therethrough; the lower portion of said latch head being reduced in external diameter and having opposed J slot connecting means formed therein, said J slot means each being open at its lower end and adapted to receive a lug therein for securing said latch head to a flow conductor, the upper portion of said latch head having the passageway therein enlarged to provide an upwardly facing stop shoulder in said passageway; means secured in said enlarged bore of said latch head above said shoulder providinga pair of opposed inwardly projecting lugs extending inwardly into said passageway and adapted to be engaged by and to cooperate with latch-n devices whereby a well tool may be secured to said latch head by means of said inwardly projecting lugs; and an internal annular groove in the passageway of said latch head below said upwardly 'facingshoulder adapted to receive locking means of a plug to be disposed in said latch head 'for securing said plug in'said latch head.

2. In combination with the latch head of claim 1, a second latch head having a passageway extending longitudinally therethrough; the lower portion of said second latch head being reduced in external diameter and having opposed J slot connecting means formed therein, said J slot means each being open at its lower end and adapted toreceive a lug therein, said upper portion of said second latch head having its bore enlarged and having the passageway therein enlarged to provide an upwardly facing stop shoulder in said passageway; means secured in said enlarged bore of said latch head above said shoulder providing a pair of opposed inwardly projecting lugs extending inwardly into said passageway and adapted to be engaged by and to cooperate with latch-on devices wherebya well tool may be secured to said second latch head by means of said inwardly projecting lugs; and an internal annular groove in the passageway of said second latch head below said upwardly facing shoulder and adapted to receive locking means of a plug to be disposed in said second latch head for securing said plug in said second latch head; said lower reduced portion of said second latch head being disposed in the large upper portion of the passageway of said first latch head, the lower end of said reduced lower portion being engageable with the upwardly facing stop shoulder of said first latch head a latch head member of the character setforth in claim 1, and a plug movable longitudinally through the passageway of said latch head and including a tubular body member having a closed lower end, said tubular body member being slidably located in a portion of the passage of said latch head, a plunger member mounted for movement in said tubular body member, and releasable latching means in the form of at least one laterally movable member carried by said tubular body member, said plunger member engaging said latching means and holding said latching means in position projecting beyond the surface of said body member to engage said internal annular groove of said latch head to hold said tubular body member in said latch head when said plunger member is in an upper position in said tubular body member, said plunger member having relief means thereon for receiving said latching means to permit said latching means to move relatively inwardly of said body member out of projecting engaging position in said groove to release said tubular body from said latch head for movement of said plug in either longitudinal direction out of said latch head upon movement of said plunger member to a lower position in said tubular body member.

4. A device for closing the bore of a well packer including: an elongate latch head having a passageway extending longitudinally therethrough; the lower portion of said latch head being reduced in external diameter and having opposed J-slot connecting means formed therein, said J-slot means each being open at its lower end and adapted to receive a lug therein for securing said latch head to a well packer, the upper portion of said latch head having the passageway therein enlarged to provide an upwardly facing stop shoulder in said passageway; means secured in said enlarged bore of said latch head above said shoulder providing a pair of opposed inwardly projecting lugs extending inwardly into said passageway and adapted to be engaged by and to cooperate with latch-on devices whereby a well tool may be secured to said latch head by means of said inwardly projecting lugs; an internal annular groove in the passageway of said latch head 'below said upwardly facing shoulder; and a plug movable longitudinally through the passageway of said latch head and releasably secured in the passageway of said latch head and having means thereon engageable with a well packer for closing the flow passage of the well packer when the latch head is secured to the Well packer, said plug having locking means thereon expansible into engagement within the annular groove of said latch head for securing said plug to said latch head, said locking means being retractible from such securing engagement within the latch head groove to free said plug from connection with said latch head for movement of said plug longitudinally out of said latch head in either longitudinal direction of the passageway of said latch head upon the exertion of a pre-determined force on said locking means in a longitudinal direction.

5. A plugging tool for use in combination with the first latch head of claim 4 after the first plug has been removed from the passageway of said first latch head and including: a second latch head having a passageway extending longitudinally therethrough; the lower portion of said second latch head being reduced in external diameter and having opposed J-slot connecting means formed therein, said J-slot means each being open at its lower end and adapted to receive a lug therein, said upper portion of said second latch head having its bore enlarged and having the passageway therein enlarged to provide an upwardly facing stop shoulder in said passageway; means secured in said enlarged bore of said latch head above said shoulder providing a pair of opposed inwardly projecting lugs extending inwardly into said passageway and adapted to be engaged by and to cooperate with latch-on devices whereby a well tool may be secured tosa'id second latch head'by means of said inwardly projecting lugs; and an internal annular groove in the passageway of said second latch head below said upwardly facing shoulder and adapted to receive locking means of a plug to be disposed in said second latch head for securing said plug in said second latch head; said lower reduced portion of said second latch head being disposed in the large upper portion of the passageway of said first latch head, the lower end of said reduced lower portion being engageable with the upwardly facing stop shoulder of said first latch head to limit downward movement of said second latch head therein; said J-slot connecting means of said second latch head engaging the inwardly projecting lugs of said first latch head for securing said second latch head to said first latch head against longitudinal movement relative thereto; and a plug movable longitudinally through the passageway of said latch head and releasably secured in the passageway of said second latch head and having means thereon extendable through the passage of the first latch head and engageable with the well packer for closing the flow passage of the well packer below said first latch head when the second latch head is secured to the first latch head, said plug having locking means thereon expansible into engagement within the annular groove of the second latch head for securing said plug to said latch head, said locking means being retractible from such securing engagement with the second latch head groove to free said plug from connection with said second latch head for movement of said plug longitudinally out of the passageways of both said latch heads upon the exertion of a predetermined force on said locking means in a longitudinal direction.

6. A device for closing the bore of a well packer including: an elongate latch head having a passageway extending longitudinally therethrough; the lower portion of said latch head being reduced in external diameter and having opposed J-slot connecting means formed therein, said J-slot means each being open at its lower end and adapted to receive a l-ug therein for securing said latch head to a well packer, the upper portion of said latch head having the passageway therein enlarged to provide an upwardly facing stop shoulder in said passageway; means secured in said enlarged bore of said latch head above said shoulder providing a pair of opposed inwardly projecting lugs extending inwardly into said passageway and adapted to be engaged by and to cooperate with latch-on devices whereby a Well tool may be secured to said latch head by means of said inwardly projecting lugs; an internal annular groove in the passageway of said latch head below said upwardly facing shoulder; and a plug movable longitudinally through the passageway of said latch head and including a tubular body member having a closed lower end and a plurality of radially spaced lateral openings, said tubular body member being located in a portion of the passageway of said latch head and having a portion extending below the lower end of said latch head and adapted to engage a well packer for closing the flow passage of the well packer when the latch head is secured to the well packer; a plunger mounted for movement longitudinally in said tubular body member; yieldable means on said body member and said plunger holding said plunger in an initial upper position in said tubular body member, said yieldable means being adapted upon application of a predetermined force longitudinally to said plunger to yield to permit said plunger to move to a lower position relative to said tubular body member; releasable latching means expansible and retractible on said plug and comprising a plurality of balls, one located in each of said lateral openings of said tubular body member and movable therein to projecting positions to engage in the annular groove of said latch head to limit relative longitudinal movement between said tubular body member and said latch head, said plunger engaging said balls to hold said balls in projecting positions to engage in the groove in said latch head when said plunger member is in said initial upper position, said plunger having release means to permit the balls to retract inwardly of the openings and the tubular body member upon the movement of said plunger to its lower position to permit the balls to withdraw from engagement with said groove so that the plug is released for movement in either longitudinal direction out of said latch head.

7. A plugging device for closing the bore of a flow conductor comprising: an elongate latch head having a passageway extending longitudinally therethrough; the lower portion of said latch head being reduced in external diameter and having opposed J-slot connecting means formed therein, said J-slot means each being open at its lower end and adapted to receive a lug therein for securing said latch head to a flow conductor, the upper portion of said latch head having the passageway therein enlarged to provide an upwardly facing stop shoulder in said passageway; means in said enlarged bore of said latch head above said shoulder providing a pair of opposed inwardly projecting lugs extending inwardly into said passageway and adapted to be engaged by and to cooperate with latch-on devices whereby a well tool may be secured to said latch head by means of said inwardly projecting lugs; an internal annular groove in the passageway of said latch head below said upwardly facing shoulder; a plug movable longitudinally through the passageway of said latch head; expansible and retractible locking means on said plug movable to an expanded position to engage said internal annular groove in the passageway of said latch head for releasably locking said plug in said passageway of said latch head, said plug having its lower portion extending outwardly beyond the passageway of said latch head; and seal means carried on the projecting portion of said plug adapted to engage the fiow conductor in which the device is located to close the bore of said flow conductor when inserted therein; said locking means on said plug being movable to retracted position to permit said plug to be moved longitudinally out of said passageway of said latch head.

8. A well tool for plugging a bore of a well packer comprising: an elongate latch head having a passageway extending longitudinally therethrough; the lower portion of said latch head being reduced in external diameter and having opposed J-slot connecting means formed therein, said J-slot means each being open at its lower end and adapted to receive a lug therein for securing said latch head to said well packer, the upper portion of said latch head having the passageway therein enlarged to provide an upwardly facing stop shoulder in said passageway; means in said enlarged bore of said latch head above said shoulder providing a pair of opposed inwardly projecting lugs extending inwardly into said passageway and adapted to be engaged by and to cooperate with latch-on devices whereby a well tool may be secured to said latch head by means of said inwardly projecting lugs; an internal annular groove in the passageway of said latch head below said upwardly facing shoulder; a plug movable longitudinally through the bore of said latch head and through the bore of said well packer; expansible and retractible locking means on said plug expansible to engagement in said internal annular groove of said latch head to releasably secure said plug to said latch head, said plug having a portion thereof projecting below said latch head; sealing means on said projecting portion of said plug engageable with the packer to close the bore of the packer when said latch head is connected to said packer; said locking means on said plug being movable to retracted position out of said internal annular groove of said latch head to free said plug for movement in a longitudinal direction out of said latch head.

(References on following page) '11" 12 References Cited by the Examiner 2,784,790 3/57 Boer et a1. 166-181 D S Reed E TA S TE S 2,928,469 11/60 Crowe 166135 7/17 Bowes 285376 3,024,845 3/62 Conrad 166'-123 12/19 Wolfe 28539 5 3,042,116 7/62 Sharp 166-224 11/38 Halllburton 2 -402 3,056,614 10/62 McClintock et a1. 28539 8/43 Coberly 285361 3,102,594 9/63 Crowe 166135 10/46 Taylor et a1. 166125 7 Leflier BENJAMIN HERSH, Primary Examiner. 7/55 Baker et a1. 166-123 10 CHARLES E. OCONNELL, Examiner. 

4. A DEVICE FOR CLOSING THE BORE OF A WELL PACKER INCLUDING: AN ELONGATE LATCH HEAD HAVING A PASSAGWAY EXTENDING LONGITUDINALLY THERETHROUGH; THE LOWER PORTION OF SAID LATCH HEAD BEING REDUCED IN EXTERNAL DIAMETER AND HAVING OPPOSED J-SLOT CONNECTING MEANS FORMED THEREIN, SAID J-SLOT MEANS EACH BEING OPEN AT ITS LOWER END AND ADAPTED TO RECEIVE A LUG THEREIN FOR SECURING SAID LATCH HEAD TO A WELL PACKER, THE UPPER PORTION OF SAID LATCH HEAD HAVING THE PASSAGEWAY THEREIN ENLARGED TO PROVIDE AN UPWARDLY FACING STOP SHOULDER IN SAID PASSAGEWAY; MEANS SECURED IN SAID ENLARGED BORE OF SAID LATCH HEAD ABOVE SAID SHOULDER PROVIDING A PAIR OF OPPOSED INWARDLY PROJECTING LUGS EXTENDING INWARDLY INTO SAID PASSAGEWAY AND ADAPTED TO BE ENGAGED BY AND TO COOPERATE WITH LATCH-ON DEVICES WHEREBY A WELL TOOL MAY BE SECURED TO SAID LATCH HEAD BY MEANS OF SAID INWARDLY PROJECTING LUGS; AN INTERNAL ANNULAR GROOVE IN THE PASSAGEWAY OF SAID LATCH HEAD BELOW SAID UPWARDLY FACING SHOULDER; AND A PLUG MOVABLE LONGITUDINALLY THROUGH THE PASSAGEWAY OF SAID LATCH HEAD AND RELEASABLY SECURED IN THE PASSSAGEWAY OF SAID LATCH HEAD AND HAVING MEANS THEREON ENGAGEABLE WITH A WELL PACKER FOR CLOSING THE FLOW PASSAGE OF THE WELL PACKER WHEN THE LATCH HEAD IS SECURED TO THE WELL PACKER, SAID PLUG HAVING LOCKING MEANS THEREON EXPANSIBLE INTO ENGAGEMENT WITH THE ANNULAR GROOVE OF SAID LATCH HEAD FOR SECURING SAID PLUG TO SAID LATCH HEAD, SAID LOCKING MEANS BEING RETRACTIBLE FROM SUCH SECURING ENGAGEMENT WITHIN THE LATCH HEAD GROOVE FOR MOVEMENT OF SAID PLUG LONGITUDINALLY OUT OF HEAD FOR MOVEMENT OF SAID PLUG LONGITUDINAL DIRECTION OF THE SAID LATCH HEAD IN EITHER LONGITUDINAL DIRECTION OF THE PASSAGEWAY OF SAID LATCH HEAD UPON THE EXERTION OF A PRE-DETERMINED FORCE ON SAID LOCKING MEANS IN A LONGITUDINAL DIRECTION. 